1. Field of the Invention
The present invention relates to composite beams or similar members, e.g. posts, formed from wooden members, and especially composite I beams.
2. Prior Art
In recent years the increasing scarcity and cost of large trees suitable for wooden joists or beams has lead to the use of composite beams, such as I beams, in which the upper and lower flanges of the beams, and the web member, are formed as separate pieces and then joined together. While in the past such beams were sometimes made of wooden pieces held together with bolts, in modern composite beams the flanges are nearly always joined to the web members by adhesive. Examples of composite beams using adhesive are shown in the following patents:
U. S. Pat. No. 4,191,000, issued Mar. 4,1980 to Henderson;
U. S. Pat. No. 4,413,459, issued Nov. 8,1983 to Lambuth;
U. S. Pat. No. 4,458,465, issued Jul. 10,1984 to Coe;
U. S. Pat. No. 4,967,534, issued Nov. 6,1990 to Lines;
U. S. Pat. No. 4,715,162, issued Dec. 29,1987 to Brightwell;
U. S. Pat. No. 5,267,425, issued Dec. 7,1993 to onysko et al., and
U. S. Pat. No. 5,323,584, issued Jun. 28,1994 to Scarlett.
The joints between the flanges and webs of such composite beams are critical to the strength of the beam, and this means that glued joints need to be made under factory conditions where presses can apply proper pressure to the joints while they set. Accordingly it is almost universal for these beams to be made in factories which are often at a large distance from the location where they will be used. The beams are usually transported in lengths of say 40 or 50 feet, and are cut into shorter lengths at a building supply depot near to the building site.
There is considerable wastage in producing and using composite beams in this way, due to the fact that builders need many different beam lengths. Typically, builders will have lengths of say 10 to 18 feet cut off from the 40 or 50 foot length, and usually this will leave short lengths which are unsaleable. This wastage contributes to the fairly high cost of these beams. The present invention allows a many different lengths of composite beam to be produced with negligible wastage.
The term xe2x80x9cbeamxe2x80x9d as used herein will be understood to refer not only to members used horizontally under floors or roofs, but also to members which may be used vertically, in the manner of posts or as vertical strengthening members used in walls.
The method of this invention can make use of T-shaped members used for forming building panels of the type described in my pending Canadian Patent Application No. 2,245,299, filed Aug. 19,1998 (corresponding to issued U. S. Pat. No. 5,901,524, issued May 11, 1999). This pending application describes several designs of T-shaped members formed from strips of material such as OSB (oriented strand board) material having flanges and webs with specially designed notches which allow the members to be readily assembled into building panels by unskilled labor. Normally, such members are 8 feet in length, and produce 8 foot square panels. The right angle joints between the webs and flanges of these members are dado joints which are strongly glued using suitable presses in factories where the notches are also cut.
A primary use of such panels is in walls, but my aforesaid copending application also describes how such panels can be connected in overlapping relationship to provide floor panels bridging widths greater than 8 feet. While these methods can provide suitable strength, there is the problem that panels connected together like this are heavy and difficult to manipulate. The present invention allows the T-shaped members which are the same or similar to those described in my pending application to be assembled into I beams which are quite light and easy to handle, and which can be used to support the panels of my pending application. Where stresses are low, the T-shaped members can be identical to the notched members of my pending application, but for higher loads it is preferred to use members which are closely similar to those of my pending application but which do not have the notches.
I have realized that the wastage involved in present production of composite I beams can largely be eliminated by producing the beams at a place of assembly or workshop near to a building site, in a manner which allows a continuous length of beam to be produced by continually adding pieces, including T-shaped members, to one end, while the required beam lengths are continually cut off from the other end. To avoid the problems with making satisfactory glued joints on site, the only such joints are the factory made joints between the flanges and the webs of the T-shaped members, and these members and any other pieces of the beams are connected together with mechanical connecting means, preferably non-metallic fastening means such as wooden pegs or bolts. The term xe2x80x9cmechanical connecting meansxe2x80x9d is intended to exclude glue. While non-metallic connecting means have the advantage that they can be sawn through without difficulty, metallic means such as nails may be used if these are such as to be removable before sawing.
More specifically, the present invention provides a process for producing varying lengths of composite wooden beams with minimal waste, in which the beams are formed from upper and lower wooden members of predetermined length each member having a longitudinal flange securely joined at a right angle to an elongated web, with the web of each upper member being connected to the web of a lower member, the process comprising:
forming a continuous beam by continually connecting additional of said members to one end of a beam portion formed of members already connected together, each additional upper member having its web connected to the web of a lower member already incorporated into the beam and each additional lower member having its web connected to the web of an upper member already incorporated into the beam, and so that the ends of upper members abut each other at joints which are staggered from similar joints between the ends of lower members, all of the webs being connected together by mechanical connecting means, and
continually cutting off required lengths of the assembled beam measured from an end of the beam portion opposite to said one end.
The reference to xe2x80x9cupperxe2x80x9d and xe2x80x9clowerxe2x80x9d members will be understood in relation to the normal orientation these parts in a horizontal beam as produced, and does not imply that the process needs to be done in any particular orientation. The reference to the ends of the members abutting does not preclude the possibility that these ends may be separated for example by shims inserted to avoid looseness at these joints.
The mechanical connecting means between the webs may be pegs or like means, such as bolts, inserted through the adjacent webs of the upper and lower members to directly connect the webs. Alternatively, instead of a direct connection between the webs of upper and lower members, the mechanical connecting means may include additional web connecting members lying in face-to face relationship with the webs of both the upper and lower members and connected thereto by pegs or like means, the end joints between the web connecting members being staggered between the joints of the upper and lower members. The web connecting members may correspond to the flanges of further, intermediate T-shaped members generally similar to either the upper or the lower members.
Where pegs are used, these may each have a front end portion terminating in a rearwardly facing abutment surface, and a rear end portion which is wider than the diameter of the aligned bores in the web and/or web connecting members. The rear end portion may terminate in a forwardly facing abutment surface, the two abutment surfaces of the peg locating against the sides of parts held by the peg. Alternatively, the peg may have rearwardly and outwardly diverging side surfaces, and the rear end portion may be merely a wide and diverging end portion of the peg which is capable of firmly pressing against the outer side of one of the connected members, so that each member is held between the wide rear end of a peg and its rearwardly facing abutment surface. Wooden or plastic pegs are preferred, and allow the beams to be produced without metallic parts so that they can be cut by saws without danger of damage to blades.
Where bolts are used, these are also preferably non-metallic; suitable bolts may be formed by cutting threads on xc2xe inch diameter wooden dowels. Wooden nuts for such bolts may be made from OSB material.
The T-shaped members used in this method are preferably similar to those of my pending application in having a strong dado joint between the flange and the web which is glued under pressure in a factory. This factory may produce both the notched members of my pending application, and notched or non-notched members, in similar or longer lengths, for producing the beams. The production method as a whole may therefore be considered as including the production of the T-shaped members as a first step by gluing together strips forming the flange and web of each member, and transporting the members to a place of assembly convenient to the building site, where the beams are produced by the method described. Assembly begins with connecting together the webs of two of the members, so that a beam portion is produced having an upper and a lower member, the flanges being spaced apart by the webs, or by web connecting members if used, and then continually adding further members to the one end of the beam portion as described.
The beam produced by the process of this invention comprises upper and lower members each member having an outer longitudinal flange secured by glue at a right angle to an elongated web, upper members of the beam being connected at end joints which are staggered relative to end joints between lower members of the beam, the webs of all members being inwardly projecting and connected together by means including mechanical fastening means such as pegs or bolts, or in some cases nails, connecting the webs. Preferably, the fastening means are non-metallic and capable of being sawn through when the beams are sawn. However, nails can be used as fastening means, if used in such a way as to be easily removed before cutting a beam.